This invention relates to laminates of metal and plastic and to their preparation. More particularly, this invention relates to novel metal-plastic-metal structural laminates which can be formed into various useful articles having compound curves using conventional metal forming techniques.
Metal plastic laminates are well known items of commerce. They include relatively thin laminates useful in flexible packaging end use applications as well as relatively thick laminates used as construction materials. Methods of preparing such laminates are also known. One method includes bringing at least one layer of plastic and at least one layer of metal into intimate contact and subjecting them to suitable heat and pressure, using, for example, a molding press. A more efficient and continuous method involves the well known extrusion processes--extrusion coating or extrusion lamination. Often an intermediate layer of adhesive or primer, in the form of a film or coating, is used in conjunction with these methods to ensure adequate adhesion between the metal substrate and plastic.
Metal plastic laminates have also been the subject of numerous patents. An exemplary selection of such patents includes U.S. Pat. Nos. 3,298,559; 3,340,714; 3,348,995; 3,382,136; 3,542,605; 3,594,249; 3,616,019; 3,711,365; 3,721,597 and 3,826,628. Most metal plastic laminates known in the art are satisfactory for many commercial uses as stated above. However, such laminates lack, among other things, satisfactory formability.
Accordingly, it is an object of this invention to provide a metal-polymer-metal structural laminate capable of being formed into an article using, for example, conventional metal-forming equipment.